Log messages for uncaught errors do not have `source` (or any other identifiable attribute)

[nadiamoe]

Brief summary

Log lines generated by uncaught errors, such as throw new Error("foobar");, do not have any identifiable attribute that allows to programatically check if the log line comes from an uncaught throwable.

Simples reproduction would be something like:

roobre@Archiroo 󱃾 curry-admin@Curry
16:56:29 /tmp/roobre $> cat throw.js

export default async function () {
  throw new Error("foobar");
}

roobre@Archiroo 󱃾 curry-admin@Curry
16:56:41 /tmp/roobre $> k6 run throw.js --log-format logfmt --log-output=file=throw.log

          /\      |‾‾| /‾‾/   /‾‾/
     /\  /  \     |  |/  /   /  /
    /  \/    \    |     (   /   ‾‾\
   /          \   |  |\  \ |  (‾)  |
  / __________ \  |__| \__\ \_____/ .io

     execution: local
        script: throw.js
        output: -

     scenarios: (100.00%) 1 scenario, 1 max VUs, 10m30s max duration (incl. graceful stop):
              * default: 1 iterations for each of 1 VUs (maxDuration: 10m0s, gracefulStop: 30s)


     data_received........: 0 B 0 B/s
     data_sent............: 0 B 0 B/s
     iteration_duration...: avg=30.22µs min=30.22µs med=30.22µs max=30.22µs p(90)=30.22µs p(95)=30.22µs
     iterations...........: 1   6937.458809/s


running (00m00.0s), 0/1 VUs, 1 complete and 0 interrupted iterations
default ✓ [======================================] 1 VUs  00m00.0s/10m0s  1/1 iters, 1 per VU

roobre@Archiroo 󱃾 curry-admin@Curry
16:56:42 /tmp/roobre $> cat throw.log
time="2024-07-12T16:56:42+02:00" level=error msg="Uncaught (in promise) Error: foobar\n\tat file:///tmp/roobre/throw.js:3:8(3)\n" executor=per-vu-iterations scenario=default

Other cases include the "browser not found in registry" error:

time="2024-07-12T16:47:49+02:00" level=error msg="Uncaught (in promise) GoError: browser not found in registry. make sure to set browser type option in scenario definition in order to use the browser module\n\tat github.com/grafana/xk6-browser/browser.syncMapBrowser.func7 (native)\n\tat file:///tmp/roobre/browser.js:20:15(4)\n" executor=shared-iterations scenario=default

k6 version

k6 v0.52.0 (commit/20f8febb5b, go1.22.4, linux/amd64)

OS

Arch linux

Docker version and image (if applicable)

No response

Steps to reproduce the problem

k6 run --log-format logfmt --log-output=file=throw.log

export default async function () {
  throw new Error("foobar");
}

Observe the matching log line does not have any attribute.

Expected behaviour

A log attribute would be nice to identify this logs programmatically and react to them. Something like source=throwable or something along those lines.

Actual behaviour

As described above.